Semiconductor devices have recently tended toward high integration. Thus, sizes of patterns of transistors used in the semiconductor devices have become remarkably minute. For example, when gate electrodes of the transistors are formed, the sizes of the patterns become minute. In the case of 45 nm generation transistors, a width of, for instance, less than 40 nm is required for gate electrodes. The patterns are formed by a process of forming a hard mask or a resist, a lithography process, an etching process, or the like.
Meanwhile, in the case of a semiconductor device employing a plurality of transistors, there is a need to make performance of each transistor uniform in order to suppress a variation in performance. In order to provide the uniform performance, a width of a gate electrode which corresponds to a flow path length affecting characteristics of the transistor is preferably made uniform. A variation in the width of the gate electrode has, for instance, an allowance of about 10%.